Method for measuring foot size and shape by using image processing

ABSTRACT

A method for acquiring information of a foot, the method includes: acquiring an image captured by simultaneously photographing a user&#39;s foot and an item having a standardized size; and calculating information of the user&#39;s foot from the image. The calculating the information of the user&#39;s foot from the image includes: calculating positions of vertices of the item from the image; and calculating a region where the user&#39;s foot is located in the image. The calculating the positions of the vertices of the item from the image includes: calculating one or more feature points corresponding to a corner in the image; and selecting the vertices of the item among the one or more feature points, and the one or more feature points are calculated by using brightness values of pixels in the image.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of U.S. application Ser. No. 16/979,111, filed on Sep. 8, 2020, which is a National Stage Entry of International Patent Application No. PCT/KR2019/002799, filed on Mar. 11, 2019, which claims priority from and the benefit of Korean Patent Application No. 10-2018-0028311, filed on Mar. 9, 2018, each of which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND Field

Embodiments of the invention relate generally to a method for measuring foot size and/or shape by using image processing.

Discussion of the Background

In most shoe manufacturing industries, shoes are manufactured by classifying only the size of the foot at 5 mm intervals without classifying the shape of the foot. There is no standardized dimension standard for each company, and even with shoes of the same size, shoes of different brands sometimes do not fit the feet. In the case of wearing shoes that do not fit the feet like this, symptoms of foot deformation such as hallux valgus may occur due to continuous compression of the shoes, and such deformation of the feet may damage the overall health of the body.

Recently, in order to prevent this risk, the technology in which the shape of a user's foot is three-dimensionally (3D) scanned to manufacture shoes considering several requirements such as the size of the user's foot, the arch, the width of feet, the toe length and the height of the instep of the foot so as to produce shoes that fit exactly to the user's foot, has been developed and used.

The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art.

SUMMARY

Method for measuring foot size and shape by using image processing according to illustrative implementations of the invention are capable of measuring foot size and/or shape automatically/semi-automatically through an image captured by a user through photographing. Thus, the user can not only easily know information about his/her own foot size conveniently, but also can receive information about shoes that do fit his/her own feet.

Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts.

According to an aspect of the present disclosure, a method for measuring foot size and shape by using image processing, includes acquiring an image captured by simultaneously photographing a user's foot and an item having a standardized size and calculating foot size or shape information from the image. The image may be captured when at least a part of the user's foot comes in contact with the item.

The item may have a rectangular shape, and the image may be photographed when all of four vertices of the item are exposed and the user's foot covers a part of edges of the item.

The calculating of the foot size or shape information from the image may include calculating positions of vertices of the item from the image and calculating a region where the foot is located in the image.

The calculating of the positions of the vertices may include calculating one or more feature points corresponding to a corner from the image, calculating a convex polygon that surrounds a contour of the item from the image and then calculating candidate points of the vertices of the item through a simplification algorithm, and comparing the one or more feature points with the candidate points to select the vertices.

The calculating of the region where the foot is located in the image, may include calculating a first region including a region where the foot and the item do not come in contact with each other, inside a figure formed by the vertices and removing the first region from the image and then calculating a contour of the other region.

The calculating of the foot size or shape information from the image may include calculating a difference between relative lengths of toes from the image to determine a shape type of the foot.

The method may further include, before the acquiring of the image, providing a guide interface to photograph the image when a part of the user's foot comes in contact with the item.

The calculating of the foot size or shape information from the image may include calculating a region where the foot is located in the image and measuring an angle of hallux valgus of the foot from the calculated foot region.

According to another aspect of the present disclosure, there is provided an application program combined with hardware and stored in a computer-readable recording medium to implement the method described above.

According to another aspect of the invention, a method for acquiring information of a foot, the method includes: acquiring an image captured by simultaneously photographing a user's foot and an item having a standardized size; and calculating information of the user's foot from the image, and wherein the calculating the information of the user's foot from the image includes: calculating positions of vertices of the item from the image; and calculating a region where the user's foot is located in the image, wherein the calculating the positions of the vertices of the item from the image includes: calculating one or more feature points corresponding to a corner in the image; and selecting the vertices of the item among the one or more feature points, and wherein the one or more feature points are calculated by using brightness values of pixels in the image.

The selecting the vertices of the item among the one or more feature points may include: calculating candidate points of the vertices; and selecting, as the vertices of the item, points which are identical to candidate points of the vertices, among the one or more feature points.

The method may further include providing a guide interface for re-acquiring the image, when a number of the candidate points of the vertices is less than a preset value.

The candidate points of the vertices may be calculated based on a closed curve having a largest area among closed curves in the image.

The calculating the information of the user's foot may include: transforming the image so that a figure formed by the vertices corresponds to the item having the standardized size.

The calculating the region where the user's foot is located in the image may include: calculating a region corresponding to the item inside a figure formed by the vertices; and removing the region corresponding to the item from the image, and the region corresponding to the item may be calculated based on the brightness values of the pixels in the image.

The method may further include providing a guide interface for re-acquiring the image based on ratio of the region corresponding to the item with respect to an entire area of the image.

When the image includes a shadow of the user's foot, the calculating the region where the user's foot may be located in the image may include: detecting a boundary between the shadow and the user's foot in the image where the region corresponding to the item is removed.

The calculating the region wherein the calculating the region corresponding to the item may include: comparing a brightness value of a first pixel and a brightness value of a second pixel adjacent to the first pixel; and determining that the first pixel and the second pixel belong to a same region when a difference between the brightness value of the first pixel and the brightness value of the second pixel is less than a preset threshold.

The first pixel may be selected by the user.

The first pixel may be selected as a point having a color value (CV) close to an intrinsic color of the item.

The image may be captured when at least a part of the user's foot comes in contact with the item.

The item may have a rectangular shape, and the image may be photographed when all of vertices of the item are exposed and the user's foot covers a part of edges of the item.

The calculating the information of the user's foot from the image may include: measuring a width or a length of the foot based on a length of a point where edges of the item and the region where the user's foot is located overlap.

The calculating the information of the user's foot from the image may include: determining a shape type of the user's foot based on a difference between relative lengths of toes of the user's foot.

The difference between the relative lengths of the toes may be determined by calculating endpoints corresponding to the toes respectively.

The calculating the information of the user's foot from the image may include: measuring an angle of hallux valgus of the user's foot based on the region where the user's foot is located.

The calculating the information of the user's foot from the imager may include: determining a severity of hallux valgus based on the angle of hallux valgus.

The method may further include, before the acquiring of the image, providing a guide interface to photograph the image when a part of the user's foot comes in contact with the item.

According to still another aspect of the invention, an application program combined with hardware and stored in a non-transitory computer-readable recording medium to execute the method of claim 1.

It is to be understood that both the foregoing general description and the following detailed description are illustrative and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate illustrative embodiments of the invention, and together with the description serve to explain the inventive concepts.

FIG. 1 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIGS. 2 and 3 are diagrams schematically showing an image used in the method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure.

FIG. 4 is a flowchart illustrating a calculating operation according to an embodiment.

FIG. 5 is a diagram showing an operation of calculating feature points.

FIGS. 6A through 6C are diagrams sequentially illustrating an operation of calculating candidate points of vertices of an item.

FIG. 7 is a diagram illustrating an operation of selecting vertices of an item.

FIGS. 8A through 8C are diagrams sequentially illustrating an operation of calculating a region where the foot is located in an image, according to an embodiment.

FIGS. 9A and 9B are diagrams illustrating a method for measuring the size of a foot according to an embodiment.

FIG. 10A through 10E are diagrams illustrating various toe shape types.

FIG. 11 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 12 is a diagram illustrating an interface for guiding a photographing method.

FIG. 13 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 14 is a diagram illustrating an interface for providing information about foot and shoes.

FIG. 15 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 16 is a diagram illustrating a method for measuring an angle of hallux valgus.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various embodiments or implementations of the invention. As used herein “embodiments” and “implementations” are interchangeable words that are non-limiting examples of devices or methods employing one or more of the inventive concepts disclosed herein. It is apparent, however, that various embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various embodiments. Further, various embodiments may be different, but do not have to be exclusive. For example, specific shapes, configurations, and characteristics of an embodiment may be used or implemented in another embodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated embodiments are to be understood as providing illustrative features of varying detail of some ways in which the inventive concepts may be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, and/or aspects, etc. (hereinafter individually or collectively referred to as “elements”), of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts.

The use of cross-hatching and/or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities between illustrated elements, and/or any other characteristic, attribute, property, etc., of the elements, unless specified. Further, in the accompanying drawings, the size and relative sizes of elements may be exaggerated for clarity and/or descriptive purposes. When an embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. To this end, the term “connected” may refer to physical, electrical, and/or fluid connection, with or without intervening elements. Further, the D1-axis, the D2-axis, and the D3-axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z-axes, and may be interpreted in a broader sense. For example, the D1-axis, the D2-axis, and the D3-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Although the terms “first,” “second,” etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,” “above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), and the like, may be used herein for descriptive purposes, and, thereby, to describe one elements relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms “substantially,” “about,” and other similar terms, are used as terms of approximation and not as terms of degree, and, as such, are utilized to account for inherent deviations in measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.

In the present specification, ‘foot size information’ or ‘shape information’ should be interpreted as a concept including all kinds of information about a user's foot. For example, ‘foot size information’ or ‘shape information’ refers to quantitative information about the length, the angle, the width, etc. such as the length of the foot, the width of feet, a distance between a specific point on the foot and another point, the width of the foot outline, the angle of three specific points of the foot, and/or qualitative information such as the shape of the outline of the foot, the shape type of the foot, the presence or absence of a foot-related disease, and the degree of the disease, but the ‘information’ of the present disclosure is not limited thereto.

A method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure may be implemented by a measuring apparatus (not shown). The measuring apparatus may correspond to at least one processor or may include at least one processor. Thus, the measuring apparatus may be driven in a form included in other hardware devices such as a microprocessor, a general-purpose computer system, a tablet, or smartphone.

FIG. 1 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIGS. 2 and 3 are diagrams schematically showing an image IMG used in the method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure. FIGS. 2 and 3 illustrate a state in which there are no other objects than an item 10 and a foot F in a background B of the image IMG for convenience of explanation.

The method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure may include acquiring the image IMG captured by simultaneously photographing the user's foot F and the item 10 having a standardized size (S120) and calculating size or shape information of the foot F from the image IMG (S140).

Referring to FIGS. 1 through 3 , acquiring of the image IMG captured by simultaneously photographing the user's foot F and the item 10 having the standardized size (S120) may be first performed. The item 10 having the standardized size may be a planar object commonly used in real life such as a paper, an envelope, a notebook, a sketch book, and a file. Hereinafter, it will be described as an example in which the item 10 having the standardized size is an A4 paper having the size of 210 mm×297 mm.

Since, in an embodiment of the present disclosure, foot size and shape is measured by using image processing, the image IMG captured by photographing the foot F is essentially used. Although FIGS. 2 and 3 illustrate the image IMG captured by photographing the bare foot F, the image IMG captured by photographing the foot F in socks may also be used. The item 10 having the standardized size may provide a reference for calculating/acquiring size information from the captured image IMG. Thus, the item 10 and the foot F may be simultaneously photographed.

In the present disclosure, the image IMG captured by photographing the user's foot F and the item 10 when at least a part of the user's foot F comes in contact with the item 10, may be image-processed so that the user's foot size may be measured. When the image IMG captured by simultaneously photographing the foot F and the item 10 in the state in which the foot F and the item 10 come in contact with each other, is used, the foot F and the item 10 may be easily distinguished from each other within the image IMG through an image processing algorithm using a color value difference.

In an embodiment, the acquired image IMG may be photographed when all of four vertices of the item 10 are exposed and the user's foot F covers a part of edges of the item 10.

Referring to FIG. 2 , the image IMG captured in a state in which the user's foot F covers a part of the edges of a vertical length of the A4 paper, is shown. The image IMG used in image analysis may be captured in a state in which both ends of the foot F come in contact with the edges of the A4 paper.

In an embodiment of the present disclosure, after coordinates of four vertices C₁, C₂, C₃, and C₄ of the item 10 are checked within the image IMG, affine transformation may be performed to be suitable for the original size and shape of the item 10 so that a size reference may be acquired to calculate the size of the foot F within the image IMG. Thus, in the acquired image IMG, all of the four vertices C₁, C₂, C₃, and C₄ of the item 10 may be exposed.

In addition, the image IMG may be captured when the foot F covers a part of edges L₁₂, L₂₃, L₃₄, and L₄₁ of the item 10. If the image IMG is captured in a state in which the foot F is located in the middle of the item 10, a part of the vertices C₁, C₂, C₃, and C₄ of the item may not be seen from the image IMG due to the leg L photographed together with the foot F. In this case, affine transformation, which is a prerequisite for securing the size reference, is not capable of being performed. Thus, the image IMG used in image processing may be captured in a state in which the foot F covers a part of the edges of the item 10 so that all of the four vertices C₁, C₂, C₃, and C₄ of the item 10 may be seen.

According to an embodiment, the image IMG may be captured in a state in which both ends of the foot F come in contact with vertical edges of the item 10. Referring to FIG. 2 , the image IMG captured in a state in which a right vertical edge L₂₃ of four edges of the A4 paper comes in contact with the foot F, is shown. Both ends, i.e., the tip of a toe end and the tip of the heel of the foot F may come in contact with the edges. In this case, the four vertices C₁, C₂, C₃, and C₄ may be recognized within the image IMG. In the case of using the image IMG shown in FIG. 2 , length information of the foot F may be easily calculated through image processing.

According to an embodiment, the image IMG may be captured in a state in which both ends of the feet come in contact with horizontal edges of the item 10. Referring to FIG. 3 , the image IMG captured in a state in which a lower horizontal edge L₃₄ of four edges of the A4 paper comes in contact with the foot F, is shown. Both ends of the feet, i.e., a left end and a right end of the foot F, may come in contact with the edges. In this case, all of the four vertices C₁, C₂, C₃, and C₄ may be recognized within the image IMG. When the image IMG shown in FIG. 3 is used, information about the width of the foot F (the length of feet) may be easily calculated through image processing.

The acquired image IMG may be pre-processed. A pre-processing operation may include a black and white image conversion operation, an adaptive sharpening operation, a blurring operation, an adaptive threshold filter application operation, and a pre-processing method is not limited thereto.

Hereinafter, a method of calculating information about the size or shape of the foot from the image IMG through image processing will be described.

FIG. 4 is a flowchart illustrating a calculating operation (S140) according to an embodiment. The calculating operation (S140) according to an embodiment may include calculating positions of vertices of the item 10 within the image IMG (S142) and calculating a region where the foot F is located in the image IMG (S144).

First, the calculating of the positions of the vertices of the item 10 within the image IMG will be described with reference to FIGS. 5, 6A, 6B, 6C, and 7 .

The calculating of the positions of the vertices of the item 10 (S142) according to an embodiment may include calculating feature points, calculating candidate points of vertices, and selecting vertices.

FIG. 5 is a diagram illustrating an operation of calculating feature points FP. According to an embodiment, the calculating of the positions of the vertices may include calculating one or more feature points FP corresponding to a corner from the image IMG. Referring to FIG. 5 , calculating of feature points FP to be determined as a ‘corner’ from the (pre-processed) image IMG may be performed. In an embodiment, a features from accelerated segment test (FAST) algorithm for extracting a corner using brightness information of a plurality of pixels corresponding to a circle boundary around each pixel may be used. An algorithm for calculating feature points FP according to the present disclosure is not limited thereto, and various corner detection algorithms such as Moravec algorithm, Harris algorithm, Shi & Tomasi algorithm, Wang & Brady algorithm, and SUSAN algorithm may be used. In the case of using the corner detection algorithm, feature points FP having the feature of a ‘corner’ such as an end of a toe in addition to actual vertices of the item 10 may be selected within the image IMG. FIG. illustrates that four vertices of the item 10 and five toe endpoints are calculated as feature points FP.

FIGS. 6A through 6C are diagrams sequentially illustrating calculating candidate points of vertices of the item 10.

Referring to FIG. 6A, extracting of a contour from the (pre-processed) image IMG may be performed. In an embodiment, Teh-Chin chain approximation algorithm may be used. However, embodiments are not limited thereto. When the extracting of the contour is performed, a contour C₁₀ of the item and a contour C_(F) of the foot may be extracted.

According to an embodiment, after the extracting of the contour is performed, selecting of a closed curve having a largest area among closed curves within the image IMG may be performed. Since, in an embodiment of the present disclosure, a A4 paper having a larger size than the foot F is generally used, it may be expected that an inner area Rio of the contour C₁₀ of the item is larger than an inner area R_(F) of the contour C_(F) of the foot. A measuring apparatus may determine the closed curve having a largest area as a closed curve of the ‘item 10’.

According to an embodiment, determining whether the ratio of the inner area Rio of the closed curve of the item with respect to the entire area of the image IMG is within a preset value, may be performed. In this case, due to the characteristics of the image IMG captured centering on the item 10 and the foot F, it may be expected that the inner area Rio of the item 10 in the image IMG is in a specific ratio of the entire area of the image IMG. For example, when the ratio of the inner area Rio of the contour with respect to the entire area of the image IMG exceeds about 20% to about 80%, the measuring apparatus may determine that no item 10 is photographed in the image IMG or the contour C₁₀ of the item is misrecognized. In this case, the measuring apparatus may provide the user with a guide interface for re-photographing the image IMG and then may re-acquire the image IMG.

Subsequently, referring to FIG. 6B, calculating of a convex polygon P that surrounds the contour of the item 10 may be performed. The convex polygon CP may be a set of points that surround the inner area Rio of the item 10 with a smallest area among points forming the contour. Sklansky algorithm may be used to find such a convex polygon CP. However, embodiments are not limited thereto. FIG. 6B illustrates that the convex polygon CP including seven points surrounds the inner area Rio of the item 10.

Subsequently, referring to FIG. 6C, calculating of candidate points CP of vertices of the item 10 through a simplification algorithm may be performed. As an algorithm for simplifying and expressing a given curve by using fewer points, Douglas-Peucker algorithm, Visvalingam algorithm, etc. may be used. However, embodiments are not limited thereto. A plurality of ‘candidate points’ may be calculated through the simplification algorithm. If the number of ‘candidate points’ is less than or equal to 3, the measuring apparatus may determine that detection of the item 10 has failed, may provide the user with an interface for guiding to re-photograph the image IMG and then may re-acquire the image IMG. FIG. 6C illustrates that five candidate points CP1 to CP5 have been detected.

FIG. 7 is a diagram illustrating selecting of vertices C₁, C₂, C₃, and C₄ of the item Previously, the ‘feature points FP’ representing the ‘corner’ and the ‘candidate points CP’ for simplifying and representing the shape of the item 10 covered by the foot F have been calculated, respectively, so that positions where the feature points FP and the candidate points CP appear in common, may be finally selected as the vertices C₁, C₂, C₃, and C₄.

For example, when there are four or more feature points FP and candidate points, only points at corresponding positions are determined and selected as the vertices C₁, C₂, C₃, and C₄ through distance comparison between a plurality of feature points FP and a plurality of candidate points.

In addition, as above, a method of automatically selecting four vertices C₁, C₂, C₃, and C₄ of the item 10 through image processing has been described. However, an operation of calculating vertices may also be performed with the user's help. For example, the user may select a position near the four vertices of the item 10 by directly touching a display unit (not shown) included in the measuring apparatus or connected to the measuring apparatus. At this time, the measuring apparatus may calculate exact coordinates of the four vertices C₁, C₂, C₃, and C₄ by using a FAST algorithm for extracting a corner only near a pixel that the user touches.

After selecting of the four vertices C₁, C₂, C₃, and C₄ of the item 10 is performed, affine transformation of the image IMG according to the size of the item 10 may be performed. For example, when the item 10 is an A4 paper, the image IMG may be affine-transformed so that a square formed by the four vertices C₁, C₂, C₃, and C₄ selected from the image IMG may correspond to a rectangle having the size of 210 mm×297 mm. Thus, a size reference for acquiring size information of the foot F may be obtained.

FIGS. 8A through 8C are diagrams sequentially illustrating an embodiment of calculating a region where the foot F is located in the image IMG.

Referring to FIG. 8A, one point or pixel A inside a boundary of the item 10 may be selected. The pixel A may be selected by the user or may be automatically selected as a point having a color value (CV) close to an intrinsic color of the item 10. For example, when the item 10 is an A4 paper, the pixel A may be selected as a pixel having a CV close to white among the central region of the image IMG.

Subsequently, comparing a brightness value of the selected pixel A with brightness values of pixels B₁ to B₈ around the selected pixel A may be performed. Referring to FIG. 8A, the measuring apparatus may compare a difference between grayscale values of a A-pixel and a B₁-pixel, for example. In this case, when a difference between brightness of two pixels is less than or equal to a preset threshold, the measuring apparatus may determine that the two pixels belong to the ‘same region’. That is, when the difference between brightness of the A-pixel and B₁-pixel is less than or equal to the preset threshold, it may be determined that the A-pixel and the B₁-pixel are in the ‘same region’. The brightness comparing may be repeatedly performed while the position of a pixel is changed. Finally, as shown in FIG. 8B, a first region R₁ that belongs to the ‘same region’ as the first A-pixel may be calculated. The first region R₁ may include a region where the foot F and the item 10 do not come in contact with each other, i.e., a region determined to correspond to the ‘item 10’. Since the first region R₁ is a region that does not correspond to the ‘foot F’, the first region R₁ may be removed when the region of the foot F is calculated.

In addition, when a shadow S of the foot F is photographed simultaneously in the image IMG captured by photographing the foot F, the shadow S is darkly photographed and thus is not determined to correspond to the ‘same region’ as the initial ‘A-pixel’ and may not be included in the first region R₁. In this case, according to an embodiment, histogram equalization may be performed in a portion excluding the first region R₁ from the image IMG. In this case, a boundary between an actual region of the shadow S and the region of the foot F appear clearly. Thus, the region of the shadow S and the region of the foot F may be clearly distinguished from each other using an edge detection algorithm such as Canny algorithm.

Subsequently, referring to FIG. 8C, after the first region R₁ is removed, a contour of the other region may be calculated so that a foot region R_(F) may be finally calculated and confirmed.

FIGS. 9A and 9B are diagrams illustrating a method for measuring the size of a foot according to an embodiment. After the region of the item 10 and the region of the foot F are calculated through image processing, the foot size such as the length of the foot F and/or the width of feet may be measured using image processing. For example, referring to FIG. 9A, a length of the foot L_F may be measured using the length of a point where the vertical edge L₂₃ of the item 10 and the region of the foot F overlap. Referring to FIG. 9B, the width of feet W_F may be measured using the length of a point where the horizontal edge L₃₄ of the item 10 and the region of the foot F overlap.

FIG. 10 is a diagram illustrating various toe shape types. According to an embodiment, calculating may include calculating a difference between relative lengths of toes from the image IMG to determine the shape type of the foot F.

When using pixel differentiation, the endpoint of the toe may be selected. In an embodiment of the present disclosure, after the image IMG is divided into regions of interest having a certain pixel, when the presence of the feature points FP within each of the regions of interest is determined and there are feature points FP, increasing the weight of the corresponding pixel and determining the presence of the feature points FP within a larger region of interest may be repeatedly performed so that a point that is likely to be the endpoint of the toe may be calculated.

After five endpoints of the toe are calculated, the shape type of the foot may be determined using a difference between positions of toes. For example, the measuring apparatus may compare the user's toe position data with foot shape type template data that has been previously stored or received from a server, to classify the user's foot type with the least error.

For example, when an index toe is long, as shown in (a) of FIG. 10 , the measuring apparatus may classify the user's foot as a first type. When the big toe is long and the length gradually decreases toward the little toe, as shown in (b) of FIG. 10 , the measuring apparatus may classify the user's foot as a second type. When the lengths of the big toe, the index toe and the middle toe are similar and the lengths of the ring finger toe and the little toe are short, as shown in (c) of FIG. 10 , the measuring apparatus may classify the user's foot as a third type. When the length of the big toe is long and the lengths of the other toes are similar, as shown in (d) of FIG. 10 , the measuring apparatus may classify the user's foot as a fourth type. When a difference between the lengths of the big toe and the index toe is not large, as shown in (e) of FIG. 10 , the measuring apparatus may classify the user's foot as a fifth type. The above-described foot types are exemplary, and a foot shape classification method of the present disclosure is not limited thereto. In addition, the measuring apparatus may determine whether the user has hallux valgus using the shape information of the foot, which will be described later with reference to FIGS. 15 and 16 .

FIG. 11 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 12 is a diagram illustrating an interface for guiding a photographing method.

The method for measuring the foot size and shape by using image processing according to an embodiment may further include, before acquiring of the image IMG (S1120), providing a guide interface to photograph the image IMG when a part of the user's foot F comes in contact with the item 10 (S1110).

Referring to FIGS. 11 and 12 , the measuring apparatus may provide/display an interface I_G for guiding a method of photographing the image IMG. Referring to FIG. 12 , the measuring apparatus may provide the guide interface I_G for photographing an image “when at least a part of the user's foot comes in contact with the item” by using a photo, a text, etc. displayed on a terminal D. In detail, the measuring apparatus may provide the guide interface I_G to photograph the image so that four vertices of the item may not be covered by the user. In more detail, the measuring apparatus may provide the photographing method guide interface I_G to photograph the image by placing the foot on the edges of the A4 paper.

Subsequently, when the user photographs the image IMG according to the photographing method guided by the interface, the measuring apparatus may acquire the image IMG (S1120) and may calculate the foot size or shape information through image processing (S1140). If the user does not have an item or photographs an image ‘incorrectly’ so that the four vertices of the item 10 are not visible, the measuring apparatus that fails to detect the four vertices may provide a guide interface to re-photograph the image.

FIG. 13 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 14 is a diagram illustrating an interface for providing information about foot and shoes.

The method for measuring the foot size and shape by using image processing according to an embodiment may further include, after acquiring of an image IMG (S1320) and calculating of the size or shape information of the foot F (S1340) are performed, providing an interface I_RCM for shoe recommendation based on the size or shape information of the foot F (S1360).

Referring to FIG. 14 , the measuring apparatus may provide an image processing result interface I_RST. In addition, the measuring apparatus may provide a shoe recommendation interface I_RCM for recommending shoes suitable for the user's foot based on the size information such as the user's foot length, the width of feet and/or shape information obtained through image processing. The shoe recommendation interface I_RCM may display information such as the photo and price of the shoes. In this case, shoes exposed to the shoe recommendation interface I_RCM may be shoes having an inner surface suitable for the user's foot size and/or shape. At this time, the measuring apparatus may provide the shoe recommendation interface I_RCM matching the user's foot size information acquired through image processing by receiving the shoe size information of various brands from a previously-stored database or server.

FIG. 15 is a time-sequential flowchart illustrating operations of a method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, and FIG. 16 is a diagram illustrating a method for measuring an angle of hallux valgus. In an embodiment of the present disclosure, the angle of hallux valgus of a patient with the symptom of hallux valgus, which is bent while the big toe joint is protruding, may be measured so that the severity of thereof may be determined.

The method for measuring the foot size and shape by using image processing according to an embodiment may include acquiring an image IMG captured by simultaneously photographing the user's foot F and the item 10 having a standardized size (S1520) and calculating size or shape information of the foot F from the image IMG (S1540). At this time, the calculating (S1540) according to an embodiment may include calculating a region where the foot F is located in the image IMG (S1542) and measuring an angle of hallux valgus of the foot from the calculated foot region (S1544).

Referring to FIGS. 15 and 16 , the measuring apparatus may calculate a region R_(F) where the foot is located, and then may calculate a bounding box BB that surrounds the foot region R_(F). For example, the bounding box BB may be a rectangle having a minimum width surrounding the foot region R_(F). In this case, the bounding box BB and the foot region R_(F) may come in contact with each other at each of a point A where the big toe protrudes upward, an endpoint B of the heel, and a point C where the big toe joint protrudes laterally. In an embodiment of the present disclosure, an angle θ formed by a line connecting the point A and the point C and a line connecting the point B and the point C may be measured as an angle of hallux valgus. A method for measuring the angle of hallux valgus is not limited thereto.

The measuring apparatus may determine the severity of hallux valgus after measuring the angle θ of hallux valgus. The measuring apparatus may classify the severity of hallux valgus into ‘steps’ according to the size of the angle of hallux valgus. For example, the measuring apparatus may determine the severity as ‘0 step’ when the angle θ of hallux valgus is less than or equal to 12 degrees. The measuring apparatus may determine the severity as ‘1 step’ when the angle θ of hallux valgus is 12 to 20 degrees. The measuring apparatus may determine the severity as ‘step 2’ when the angle θ of hallux valgus is 20 to 30 degrees. The measuring apparatus may determine the severity as ‘step 3’ when the angle θ of hallux valgus is 30 to 50 degrees. The measuring apparatus may determine the severity as ‘step 4’ when the angle θ of hallux valgus is greater than or equal to 50 degrees. The number and numerical values of the above steps are exemplary and do not limit the present disclosure.

The measuring apparatus may provide an interface indicating severity information of hallux valgus. For example, the measuring apparatus may provide an interface displaying information ‘this step is an initial step of a hallux valgus symptom and thus please pay attention to shoe selection’, when the measured severity is at step 1. In addition, the measuring apparatus may provide an interface for recommending shoes that are comfortable for hallux valgus patients or a hospital specializing in hallux valgus or displaying lifestyle information required for hallux valgus patients, based on the angle θ of hallux valgus or information about the severity of hallux valgus.

The method according to the above-described embodiment may be implemented in the form of programs and application program instructions that can be executed through various computer means, and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and a hardware device specially configured to store and execute program instructions such as ROMs, RAMS, flash memory, and the like. Examples of the program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

The above-described method of the present disclosure can be executed through an application program stored in a computer-readable recording medium in combination with hardware such as a mobile device such as a smartphone and a tablet. For example, the user photographs the foot F and the item 10 by using a camera built into the smartphone and uploads it to the application program. The application program may analyze the image uploaded/input by the user, measure the size and shape of the user's foot, and recommend shoes matching the user's foot size information.

In the method for measuring foot size and shape by using image processing according to an embodiment of the present disclosure, the user can measure the foot size and/or shape automatically/semi-automatically through an image captured by a user through photographing. Thus, the user can not only easily know information about his/her own foot size conveniently, but also can receive information about shoes that do fit his/her own feet.

According to the present disclosure, a method for measuring foot size and shape by using image processing is provided. In addition, embodiments of the present disclosure may be applied to an industrially used apparatus for measuring the inner size of an object in which an inner space is formed, by using image processing.

Although certain embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as would be apparent to a person of ordinary skill in the art. 

What is claimed is:
 1. A method for acquiring information of a foot, the method comprising: acquiring an image captured by simultaneously photographing a user's foot and an item having a standardized size; and calculating information of the user's foot from the image, wherein the calculating the information of the user's foot from the image comprises: calculating positions of vertices of the item from the image; and calculating a region where the user's foot is located in the image, and wherein the calculating the positions of the vertices of the item from the image comprises: calculating one or more feature points corresponding to a corner in the image; and selecting the vertices of the item among the one or more feature points, and wherein the one or more feature points are calculated by using brightness values of pixels in the image.
 2. The method of claim 1, wherein the selecting the vertices of the item among the one or more feature points comprises: calculating candidate points of the vertices; and selecting, as the vertices of the item, points which are identical to candidate points of the vertices, among the one or more feature points.
 3. The method of claim 2, further comprising providing a guide interface for re-acquiring the image, when a number of the candidate points of the vertices is less than a preset value.
 4. The method of claim 2, wherein the candidate points of the vertices are calculated based on a closed curve having a largest area among closed curves in the image.
 5. The method of claim 1, wherein the calculating the information of the user's foot comprises: transforming the image so that a figure formed by the vertices corresponds to the item having the standardized size.
 6. The method of claim 1, wherein the calculating the region where the user's foot is located in the image comprises: calculating a region corresponding to the item inside a figure formed by the vertices; and removing the region corresponding to the item from the image, and wherein the region corresponding to the item is calculated based on the brightness values of the pixels in the image.
 7. The method of claim 6, further comprising providing a guide interface for re-acquiring the image based on ratio of the region corresponding to the item with respect to an entire area of the image.
 8. The method of claim 6, when the image includes a shadow of the user's foot, wherein the calculating the region where the user's foot is located in the image comprises: detecting a boundary between the shadow and the user's foot in the image where the region corresponding to the item is removed.
 9. The method of claim 6, wherein the calculating the region wherein the calculating the region corresponding to the item comprises: comparing a brightness value of a first pixel and a brightness value of a second pixel adjacent to the first pixel; and determining that the first pixel and the second pixel belong to a same region when a difference between the brightness value of the first pixel and the brightness value of the second pixel is less than a preset threshold.
 10. The method of claim 9, wherein the first pixel is selected by the user.
 11. The method of claim 9, wherein the first pixel is selected as a point having a color value (CV) close to an intrinsic color of the item.
 12. The method of claim 1, wherein the image is captured when at least a part of the user's foot comes in contact with the item.
 13. The method of claim 1, wherein the item has a rectangular shape, and the image is photographed when all of vertices of the item are exposed and the user's foot covers a part of edges of the item.
 14. The method of claim 1, wherein the calculating the information of the user's foot from the image comprises: measuring a width or a length of the foot based on a length of a point where edges of the item and the region where the user's foot is located overlap.
 15. The method of claim 1, wherein the calculating the information of the user's foot from the image comprises: determining a shape type of the user's foot based on a difference between relative lengths of toes of the user's foot.
 16. The method of claim 15, wherein the difference between the relative lengths of the toes is determined by calculating endpoints corresponding to the toes respectively.
 17. The method of claim 1, wherein the calculating the information of the user's foot from the image comprises: measuring an angle of hallux valgus of the user's foot based on the region where the user's foot is located.
 18. The method of claim 17, wherein the calculating the information of the user's foot from the imager comprises: determining a severity of hallux valgus based on the angle of hallux valgus.
 19. The method of claim 1, further comprising, before the acquiring of the image, providing a guide interface to photograph the image when a part of the user's foot comes in contact with the item.
 20. An application program combined with hardware and stored in a non-transitory computer-readable recording medium to execute the method of claim
 1. 